The Olympus OM-D E-M10 Mark IV is the most recent entry-level OM-D, as of 2020. Compared to its predecessor, Olympus upgraded the image sensor to a 20 megapixel unit, already known from various higher-end OM-D models. Furthermore, the burst mode reaches about 15 fps and the internal buffer catches over 40 RAW images - both almost doubling its predecessors performance.
If you want to achieve the maximum speed for continuous shooting, you should use SDHC or SDXC memory cards with an UHS-II interface for the Olympus OM-D E-M10 Mark IV. For video recordings in 4K quality, it should be at least one card with a SD Speed Class of U3/V30.